Traditional valve spring retainers, such as those used in most automobiles, are made out of steel. In high performance racing (NASCAR, etc.), engine performance is measured in grams of weight removed from the valve train, so valves and spring retainers that are lighter can substantially improve the performance of the engine. Aluminum is generally too soft and not strong enough to be used for valve spring retainers, while steel is generally too heavy. It is known to use titanium as an alloy for valve spring retainers because it is about 40% lighter than steel for comparable strength. However, in high performance racing engines the titanium can gall or wear too easily. For example, in a 500 mile Winston Cup race the wear surface on the retainer can loose up to about 0.060″ of material, or installation height, by race end. This loss of material can equate to a 5–10% loss of power in the engine. As races are typically won and lost in the last 25 laps, it is apparent that the valve spring retainer wear can have a significant impact on the success of any racing team or car.
In the past, various attempts to address the wear problem have been made, including attempts to coat the spring seat with a wear resistant coating, having a thickness in the range of about 50–100 millionths of an inch, such as Chrome, Diamond Like Carbon (DLC) using impingement (shot peening), and Titanium Nitride. However, such attempts have not proved especially satisfactory.
Accordingly, it would be desirable to provide a valve spring retainer that is lighter than steel and yet has improved wear characteristics over previously known titanium alloy valve spring retainers.